Will boiling water crack the windscreen?

“Will boiling water crack the windscreen?” is a common question asked on frosty mornings by many drivers.


Chloe Profile Picture

By Chloe Martell

Updated on Dec 10th, 2020

Will boiling water really crack your car windscreen? And if so, what's the best way to deice your car when you’ve not got deicer to hand? (It's definitely not using a CD case as a makeshift scraper, I mean, who even has CD cases any more?)

How to defrost your windscreen without deicer

Sure, most people use an ice scraper and deicer to clear off our windscreens on a frosty morning, but some of us think that's a little boring. So we put together some quirky ways to both deice your car and mix things up in the morning, variety is the spice of life after all.

Even if you have a preference for the classic deicer approach, it's easy to run out in particularly frosty winters - so here are some alternatives

Will boiling water crack the car windscreen?

In short, yes. This isn't an old wives tale or car driving myth, boiling water + car windscreen is not a combination you want to put together all that often.

“But I’ve tried this before and it was fine” we hear you cry. And sure, it's not going to crack every time, but it happens, more often than you think. At the very least you're putting unnecessary stress on your car windscreen that might culminate over time.

If that's not enough, there's a very real risk that the hot water will freeze on the floor causing a slip hazard! Whilst the ‘hot water freezes faster than cold water’ belief is less true than you might think, it still freezes!

Use lukewarm/ room temperature water instead?

We are advocates of using lukewarm water to defrost your car windscreen instead, although you will need to be careful as if it is very cold the water than runs of the windscreen onto the road or drive may re-freeze and cause a slip hazard.

It's worth pointing out that you might still need to wipe away some icy residue with a cloth, but this is a pretty speedy way of clearing your windscreen.

Try warm water in a bag to defrost your car windscreen

The genius here is in its simplicity. We all have access to hot water, and we all have an old ziplock bag or freezer bag lying around somewhere. Simply put those two things together and your car windscreen will be first free in no time.

How to defrost your car with a ziplock bag and water?

If you haven't managed to figure out the method already you’re going to kick yourself.

Step 1. Put warm water in a ziplock bag

Step 2. Rub bag over your windscreens 

Step 3. Take a step back and marvel at your newly clear windscreen (and toasty warm hands) 

Use rubbing alcohol to deice your car

You know all those bottles of rubbing alcohol you have sitting around and you’re trying to figure out what to do with it? Well mix ⅓ water with ⅔ rubbing alcohol and you’ve got yourself some homemade deicer!

(We did a quick poll and none of us have any rubbing alcohol in the house either, but still we’ve been assured this is really effective.)

Make A Water And Salt Solution

It's no secret that salt lowers the freezing point of water and defrosts ice. We’ve all been taught that since primary school, and that is of course why there’s salt all over the roads and paths in the winter. It’s not just there to ruin your brand new shoes (I’m still not over an incident in the winter of 2017, it was a sad day for footwear), it's there to prevent ice from forming. So you have two options here, spray your salt water solution on your windscreen the night before to prevent ice forming, or use it to deice in the morning. Or play it safe and do both! Just wear plastic bags over your shoes or something.

Using a soaked towel to prevent your windscreen icing over

They say that medically, prevention is better than the cure. And the same applies to car windscreens (someone give me a doctorate already)! Simply soak a towel in salt water solution, place it on your windscreen the night before and it should keep your windscreens frost free.

Or just use a windscreen cover!

Fan of frost free windscreen but not wet salty towels? You can save yourself a lot of hassle by just buying a windscreen cover. They’re not particularly pricey, especially when you value all the time you’ll be saving. You can also pop plastic bags on your wing mirrors, secure them with rubber bands and they’ll be clear in the morning too.

Leave a hot water bottle on your dashboard and enjoy your breakfast

We love this idea, it's so idyllic. Simply put a hot water bottle on your dashboard, then enjoy a couple rounds of toast and a nice hot coffee, and by the time you’re done the hot water has melted the ice away.

Unfortunately, in our experience it doesn't quite work like that. Unless you have a particularly tiny car, one hot water bottle probably wont do the trick - and no one wants to fill six of them and line them up along the dash every morning. Still we do find that placing one or two in your car for ten to fifteen minutes can start the thawing process and make one of the other solutions work a little more effectively.

Park facing east

Talking about starting the thawing process. This one is surprisingly effective. If you can - park facing the east. (That's where the sun rises in case you've forgotten your year three geography lessons.)

Even the weak winter son has enough about it to start thawing ice, its low effort and will make any of the other solutions much easier and more effective.

Use a Spatula to deice your car?

No. Just no. Unless you want to replace your windscreen every year that is. Would you believe we found four different articles online suggesting this as a solution? It’s not.

A proper, well designed scraper, does work wonders however. Just try to avoid the ones for 50p on Amazon, you probably want to be looking around the £15-£20 mark to get one that will work really well without risking damage to your windscreen.

Try deicer the night before?

I know, I know, we said that these were solutions which don't need a device. But the way we see it is that one of the big issues with deicer is that it's so cold in the morning that your hands freeze and your day starts off on a pretty bad note. So how about applying a deicer the night before? The can is less cold, and you can head inside after to worm your hands on a mug of hot chocolate.

The downside? It doesn't really work. Even the ‘night before deicer’ available in some shops get pretty bad reviews.

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Chloe Profile Picture

By Chloe Martell

As a new driver, I'm so eager to share my driving journey with you all - from when I was a learner, going through my test and all the aspects of my driving life now, including my love of cars!


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